Preheat your oven to 375°F (190°C).
In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, garlic, Italian seasoning, salt, and pepper.
Mix well and form into meatballs, about 1 inch in diameter.
In a large skillet, brown the meatballs over medium heat until cooked through.
Remove the meatballs and drain excess fat.
In a baking dish, spread half of the marinara sauce on the bottom.
Place the meatballs on top of the sauce.
Pour the remaining marinara sauce over the meatballs.
Sprinkle mozzarella cheese evenly over the top.
Bake in the preheated oven for 25-30 minutes, until the cheese is bubbly and golden.